Chocolate bars such as Kit-Kat, Yorkie and Aero will contain 10pc less sugar by next year, manufacturer Nestle has announced.
The sugar will be replaced with higher quantities of existing ingredients or other, non-artificial ingredients.
The amount of calories will be limited.
The move will see around 400 tonnes of sugar removed across a number of well-known brands in Ireland through a range of methods and initiatives.
Nestle said it could help to have a significant impact on public health.
Last year, Nestlé announced it had made a scientific breakthrough that has the potential to reduce sugar in its treats by up to 40pc, without affecting the taste.
The company said it was securing a patent for its innovation, and it would start using the new sugar substitute across its range from 2018.
Fiona Kendrick, chairman and CEO of Nestle UK and Ireland, said: "Our confectionery brands have been enjoyed for more than a century and we know that if we can improve these products nutritionally, provide more choice and information for the consumer... we can have a significant impact on public health."
The news comes after an announcement earlier this month that Irish ice cream laws dating back to 1952 are being revised in an effort to fight national obesity levels.
The planned changes will revise the content of milk-fat, milk solids and sugar content in ice cream.